WordReference Random House Unabridged Dictionary of American English © 2020
em′bryon′ic disk′, [Embryol.]
- Developmental BiologyAlso called em′bryon′ic shield′. in the early embryo of mammals, the flattened inner cell mass that arises at the end of the blastocyst stage and from which the embryo begins to differentiate.
- Developmental Biologythe blastodisk of yolky eggs.